Structure of niobium phosphate glasses with non-linear optical properties

The addition of Nb2O5 to phosphate glasses improves the chemical durability, increases the refractive index, and imparts non-linear optical properties, which opens-up the possibility of innovative applications in optical waveguiding. The non-linearity is achieved without the incorporation of toxic components such as lead, which has a beneficial environmental and health impact. To optimise the material properties, it is important to know their dependence on the glass structure. The composition dependence of the Nb coordination environment is, however, an unknown quantity. We propose to remedy this situation by using neutron diffraction to study the structure of glasses in the model system Nb2O5-NaPO3. The results will be combined with those from solid-state NMR experiments to build a comprehensive picture of the network connectivity and how it is influenced by varying the Nb content.